BRIQUETTING OF TITANIUM SHAVINGS BY MEANS OF SHORT ELECTRICAL PULSES

摘要

At present, the main source of secondary raw materials in metallurgy is metal shavings (especially shavings of high-strength metals). The difficulty of processing such secondary materials is associated with their low volume density and the lack of efficient tools and technologies suitable for their loading-unloading. The latter is needed for transportation and loading production apparatuses. The existing briquetting methods use large compacting forces (3-4 ton/cm~2), sometimes in combination with heating of the shavings, which makes it possible to obtain briquettes with a density equal to 50-70 percent of the metal's density. Nevertheless, even at such densities, the strength of briquettes is sometimes insufficient (1).The problem of compacting metal shavings into briquettes is especially acute for titanium alloys. Production of items from titanium alloys usually requires especially large amounts of shavings: their mass is normally equal to the mass of the end product. Titanium shavings are non-magnetic and their density is lower than that for steel shavings, which makes their transport even more difficult and prevents full utilization of the load capacity of transport facilities. The existing industrial technology of titanium alloy smelting in vacuum-arc furnaces allows utilization of no more than 15 percent of titanium shavings that make up apart of the expendable first-melting electrode. This technology therefore does not allow for using titanium shavings in significant amounts, i.e., as part of the charge in production of secondary alloys and cast titanium products, where their utilization would be most beneficial (2). Shavings of titanium alloys can be compacted into briquettes at pressures of up to 9 ton/cm~2 or under heating in vacuum or in an inert gas atmosphere (3-5). This, however, turns out to be economically prohibitive. As a result, the existing technology produces excess amounts of titanium alloy shavings (2).